This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 6 |
| 4 | 18 |
| 5 | 50 |
| 6 | 290 |
| 7 | 2582 |
| 8 | 20462 |
| 9 | 23870 |
| 10 | 26342 |
| 11 | 31938 |
| 12 | 38122 |
| 13 | 65034 |
| 14 | 70130 |
| 15 | 245538 |
| 16 | 851878 |
| 17 | 1052422 |
| 18 | 1496566 |
| 19 | 5380542 |
| 20 | 8431178 |